1. Field of the Invention
The invention relates, e.g., to three dimensional structural systems made from interlocking planar sheets of material. The structural system of the invention provides, e.g., sturdy interlocked columns and shelves that are easy to assemble from a minimum of material. The structural system can be configured, e.g., to provide attractive, inexpensive, and functional furniture.
2. Description of Related Art
There exists a wide range of structural frame, furniture, and shelving systems. Box frames are ancient and still common systems for framing structures. Box frames have been used, for example in buildings, transportation systems, and furniture. The outer walls of such box frames receive compressive forces while supporting tops or shelves. Such frames can contain a large volume without excessive use of materials but provide weak support in central horizontal regions of the structure. Box frame structures can also be heavy because shear walls may be required to prevent diamonding of edge supports. Without such “shear walls” to prevent articulation at the joints between the base, walls, and top, the whole structure can collapse when the structure is under the stress of lateral forces.
With the appearance of modem materials and designs, elegant central column structures have become more common, especially in architecture. Structures with central frame members have the advantage of lightness and openness. Tall buildings have evolved from cathedrals with heavy outer buttressed structural walls to skyscrapers with internal steel and concrete support columns supporting lighter outer walls. Central columns are located near the center of the weight they support, so horizontal surfaces can be lighter without sagging. Center supports allow outer non-structural walls and floors to be lighter and more open to light and movement. For example, modem skyscrapers often have an internal frame of structural columns so that offices can enjoy abundant windows and maximum peripheral floor space without the intrusion of heavy external structural walls or columns.
The internal frames of buildings are usually made up of a multitude of vertical and horizontal steel beams that are attached to each with rivets or bolts. A typical beam for these frames in an “I-beam” having a cross section shaped like the letter I to provide strength in two dimensions against lateral forces while the beam as a whole provides compressive or tensile strength in the axial dimension. Such beams systems are weakest at the joints where they bolt together and can be quite bulky to transport.
Shelving has also evolved from heavy outer box frame designs, to lighter units mounted on walls or supported on poles. Yet, many of the modern designs trade bulky support systems for thinner central supports dependent on expensive modern materials. Some shelving, such as the system described in U.S. Pat. No. 5,148,928, “Shelf System”, to Arnold, provide thin outer support columns. The Arnold shelf system uses a minimum of materials while providing easy access and view of objects placed on the shelves. However, the columns must be made from a strong material, such as steel, and the shelf system is not free standing. Other light weight shelving systems include metal tracks that must be mounted to a wall for support of mounting brackets and shelves. Again, this system uses a minimum of materials but must be mounted to another structure for support. It has been observed that metal shelving systems of these types do not have a pleasing appearance.
A need remains for a structural system of columns and shelves that is light and strong that uses a minimum of simple materials to construct. It is desirable to have free standing support columns for floors or shelving that do not require bulky walls that block passage of objects or light. The present invention solves these problems, as will be made evident in the disclosure that follows.